Add .mailmap
Add .mailmap

I don't know why I like these things but I do.  `git shortlog` will
read .mailmap and coalesce authors.  This mailmap cleans up most of
the dups I could find.

Signed-off-by: Steven Danna <9ce5770b3bb4b2a1d59be2d97e34379cd192299f@chef.io>

chef/chef-server,itmustbejj/chef-server,marcparadise/chef-server,juliandunn/chef-server-1,marcparadise/chef-server,juliandunn/chef-server-1,marcparadise/chef-server,chef/chef-server,juliandunn/chef-server-1,chef/chef-server,juliandunn/chef-server-1,marcparadise/chef-server,marcparadise/chef-server,chef/chef-server,itmustbejj/chef-server,itmustbejj/chef-server,chef/chef-server,juliandunn/chef-server-1,chef/chef-server,itmustbejj/chef-server,itmustbejj/chef-server